U.S. Pat. No. 4,321,073 describes a device for providing a metal coating on a glass fibre, using infrared light which is transmitted, for example, from a laser to the glass fibre by means of optical conductors. The exit windows of the optical conductors are smoothly polished and a diverging beam of infrared light is employed.
It is an object of the invention to provide an irradiation device in which during its operation the light generated by the light source is transmitted very effectively and with a high intensity to the location of the object to be irradiated, in particular when this object is a filamentary body.